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Method for rounding bottom corners of trench and shallow trench isolation process

Active Publication Date: 2006-05-25
UNITED MICROELECTRONICS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] Accordingly, the present invention provides a method for rounding the bottom corners of a trench and a STI process wherein the bottom corners of the trench is rounded effectively.
[0010] By using a fluorocarbon compound with at least two carbon atoms, He and O2 as an etching gas, the polymer residues at the bottom of the trench can be removed completely, and the bottom corners of the trench can be rounded effectively. Therefore, the problems in the prior art, such as, high stress or point discharge, can be solved.

Problems solved by technology

Hence, with device miniaturization, isolating structures are increasingly difficult to fabricate.
However, when the device linewidth becomes smaller, for example, under 90 nm, it is difficult to round the bottom corners of each trench (100) with Cl2 or HBr as an etching gas, as shown in FIG. 1.
This may result in some problems, such as, high stress or point discharge, at the bottom corners 104 of each trench 100.

Method used

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  • Method for rounding bottom corners of trench and shallow trench isolation process
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Embodiment Construction

[0016] Reference will now be made in detail to the present preferred embodiments of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

[0017]FIGS. 2A through 2C are schematic cross-sectional views showing the steps of a STI process according to the preferred embodiment of this invention. As shown in FIG. 2A, a pad layer 202 and a mask layer 204 are sequentially formed over a substrate 200. The pad layer 202 and mask layer 204 are then patterned to form an opening 206 that exposes a portion of the substrate 200. The pad layer 202 may be a silicon oxide layer formed with, for example, thermal oxidation. The mask layer 204 may be a silicon nitride layer formed with, for example, LPCVD. The mask layer 204 and the pad layer 202 can be patterned using a patterned photoresist layer as an etching mask, which is removed after the patterni...

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Abstract

A method for rounding the bottom corners of a trench is described. In the method, an etching process is performed using a fluorocarbon compound with at least two carbon atoms, He and O2 as an etching gas to round the bottom corners of the trench.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor process. More particularly, the present invention relates to a method for rounding the bottom corners of a trench and a shallow trench isolation (STI) process. [0003] 2. Description of the Related Art [0004] Due to the rapid development of integrated circuit technologies, device miniaturization and integration are the major trends in semiconductor manufacturing industry. As the dimension of device continues to be shrunk and the degree of integration continues to be increased, isolation structures have to be miniaturized correspondingly. Hence, with device miniaturization, isolating structures are increasingly difficult to fabricate. The preferred isolation structure for sub-micron MOS devices is the STI structure, because it is scalable without causing any bird's beak encroachment problem as in the conventional local oxidation of silicon (LOCOS) process. [0005] In a c...

Claims

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Application Information

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IPC IPC(8): H01L21/76
CPCH01L21/76232
Inventor HUANG, KAO-SU
Owner UNITED MICROELECTRONICS CORP